class A
init do end
end
-
class B
special A
meth foo do 0.output
init do end
end
-
class C
special B
meth bar do 1.output
init do end
end
+
+#alt5# var b: A = new B
var a: A = new C
-#alt5# a = new B
+#alt5# a = b
#alt6# a = new A
if a isa B then
a.foo